common/board_f: remove XTRN_DECLARE_GLOBAL_DATA_PTR dead code
The XTRN_DECLARE_GLOBAL_DATA_PTR declarations in ppc code are permanently
commented out, so there are no users for this macro:
#if 1
#define DECLARE_GLOBAL_DATA_PTR register volatile gd_t *gd asm ("r2")
#else /* We could use plain global data, but the resulting code is bigger */
#define XTRN_DECLARE_GLOBAL_DATA_PTR extern
#define DECLARE_GLOBAL_DATA_PTR XTRN_DECLARE_GLOBAL_DATA_PTR \
gd_t *gd
#endif
Remove all references to this macro, but add a documentation note regarding
the possibility of using plain global data for the GD pointer.
Signed-off-by: Ovidiu Panait <ovpanait@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/doc/develop/global_data.rst b/doc/develop/global_data.rst
index 2ac893d..d143f27 100644
--- a/doc/develop/global_data.rst
+++ b/doc/develop/global_data.rst
@@ -36,6 +36,11 @@
The sandbox, x86_64, and Xtensa are notable exceptions.
+Current implementation uses a register for the GD pointer because this results
+in smaller code. However, using plain global data for the GD pointer would be
+possible too (and simpler, as it does not require the reservation of a specific
+register for it), but the resulting code is bigger.
+
Clang for ARM does not support assigning a global register. When using Clang
gd is defined as an inline function using assembly code. This adds a few bytes
to the code size.